Needle carrier for tandem needle sewing machine

ABSTRACT

A needle carrier for an overseaming machine having a pair of spaced needles aligned in the direction of feed of the workpiece through the machine. The needle carrier includes a head portion having a flat vertical face with an elongated keyway formed therein, and a clamping plate having an elongated key formed on one surface is releasably mounted on the head with the key projecting into the keyway. A pair of grooves are formed in the plate, one on each side of the key, to engage and position the shanks of the pair of needles for clamping between the plate and the flat face on the head portion of the carrier. Any desired needle spacing may readily be obtained by employing a clamping plate having grooves appropriately spaced.

United States Patent 3,373,706 3/1968 Armstead ABSTRACT: A needle carrier for an overseaming machine having a pair of spaced needles aligned in the direction of feed of the workpiece through the machine. The needle carrier includes a head portion having a flat vertical face with an elongated keyway formed therein, and a clamping plate having an elongated key formed on one surface is releasably mounted on the head with the key projecting into the keyway. A pair of grooves are formed in the plate, one on each side of the key, to engage and position the shanks of the pair of needles for clamping between the plate and the flat face on the head portion of the carrier. Any desired needle spacing may readily be obtained by employing a clamping plate having grooves appropriately spaced.

PATENTEU AUG] 019m FIG. I

FIG. 2

INVENTOR GEORGE B. ARMSTEAD, JR.

ATTORNEYS.

NEEDLE CARRIER FOR TANDEM NEEDLE SEWING MACHINE This invention relates to sewing machines, and is particularly concerned with a needle carrier for use in an overseaming machine employing two sewing needles mounted in tandem along the length of a seam formed by the machine. More specifically, this invention relates to an improved needle carrier for use in a sewing machine of the type illustrated in my US. Pat. No. 3,373,706.

In conventional overseaming machines employing a single needle, a workpiece is fed through the machine in intermittent increments by a feed mechanism whose movement is coordinated with movement of a thread carrying needle which passes loops of thread through the workpiece during the dwell between successive feed increments. In such machines, the length of a stitch formed by the machine may readily be varied by an adjustment of the feed mechanism, which adjustment normally constitutes installation of an appropriate feed eccentric to produce the desired feed motion.

In the sewing machine described in my prior patent, mentioned above, the length of the individual stitches is still controlled by the adjustment of the feed mechanism in the conventional manner. However, in such a machine, the relation between the spacing of the two aligned needles to the length of the individual feed increments has a definite bearing on the spacing of stitches formed by one needle with respect to those formed by the other needle. In order for the stitches formed by the rear needle to be positioned precisely halfway between the stitches formed by the forward needle, thereby creating the illusion of a seam formed with a single needle thread, the needles themselves must be spaced apart a distance equal to either one half the length L of a feed increment or any whole number n multiple plus one half the length of a feed increment, i.e., 96L or M. +kL.

From the above, it becomes apparent that in order to maintain the desired relation between stitches formed by the two needles, it will normally be necessary to adjust the needle spacing each time the stitch length is changed. However, in the prior art overseaming machines the needles have normally been retained in fixed position on the needle carrier and therefore have not readily lent themselves to the adjustment of the needle position, with the result that any required adjustments were normally made by physically bending the needles. This practice, when attempted in a tandem needle machine, produced only approximate needle spacing, and frequently resulted in broken or permanently damaged needles. Accordingly, it is a primary object of the present invention to produce an improved needle carrier for tandem needle sewing machines.

Another object is to provide an improved needle carrier for a tandem needle sewing machine which makes it possible to quickly and accurately adjust the spacing of the two needles.

In the attainment of the foregoing and other objects, one feature of the invention resides in providing a needle carrier with a flat vertical face disposed parallel to the path of a workpiece through the machine and against which a flattened surface on the shanks of the needles are clamped, and providing a clamping plate with accurately positioned spaced grooves for engaging and clamping the needle shanks against the flat face. A keyway on the carrier head receives a key on the clamping plate to accurately align the grooves, and a threaded fastener extending through the carrier head is employed to tighten the clamp in place to retain the needles. Loosening of the single, readily accessible fastener makes it possible to quickly and easily change the clamping plate. A plurality of clamping plates each having different spaced slots, would normally be provided with each machine so that accurate needle spacing could readily be supplied for any standard feed eccentric size.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment of the invention, taken in conjunction with the drawings, in which:

FIG. 1 is a fragmentary end elevation view of an improved overseaming machine embodying the invention;

FIG. 2 is a sectional view of the needle carrier, taken on line 22 ofFIG. l; and V v 5 FIG. 3 is an exploded perspective view. of the components of the needle carrier illustrated in FIG. 2.

Referring now to the drawings in detail, the invention is illustrated as embodied in a well-known Merrow overseaming machine which has been modified in accordance with my prior patent, mentioned above, to include a pair of lower loopers 12, 14 and a pair of upper loopers I6, 18 which cooperate with a pair of needles 20, 22 to simultaneously form two independent sequences of stitches aligned in the direction of feed of a workpiece through the machine to form a single overedge seam. Needles 20, 22 are supported by a needle carrier 24 which includes an arm 26 having a tapered journal bearing 28 formed in one end and adapted to be pivotally supported on a tapered shaft 30 mounted on machine frame 32. 1

driven through the machine by the conventional feedmechanism, not shown.

Referring now particularly to FIGS. 2 and 3, it is seen that the needle carrier 24 terminates at oneend in a head portion 44 having a flat vertical face 46 which is disposed in a vertical plane perpendicular to the pivot axis of the needle carrier and parallel to the direction of feed of the workpiece through the machine. An elongated, rectangular keyway 48 is formed in face 46 and extends across the head 44. A bore 50 extends through head 44 normal to face 46 with its axis intersecting the longitudinal centerline of keyway 48, and a countersink 52 having one flattened wall 54 is formed in the back surface 56 of head 44 for receiving the head 58. of a bolt 60. As most clearly seen in FIG. 3, bolt head 58 has a flattened face 62 for engaging wall 54 to prevent rotation of bolt 60 relative to head 44. A nut 64 is adapted to be threadably received on the end of bolt 60.

A clamping plate 68 having a substantially fiat surface 70 with a rectangular key 72 integrallyformed thereon and projecting outwardly therefrom has a bore 74 extending therethrough for mounting on bolt 60. Key 72 fits snugly within keyway 48 to accurately position clamping plate 68 on head 44 and positively prevent relative rotation therebetween when the nut 64 is tightened onto bolt 60. A pair of spaced grooves 76, 77 are formed in flat surface 70, one on each side of key 72. Grooves 76, 77 each have a cross section in the configuration of an isosceles trapezoid, and are dimensioned to engage the cylindrical surface on the shank portion (FIG. I) of needles 20, 22, respectively. The needles 20, 22, are provided with a flat surface 80, 81, respectively, along their shank portions for engaging the flat face 46 of head 44 to accurately align and position the curved blade portion of the needles in the desired radial spacing relative to the pivot axis of the needle carrier.

From the above it is readily apparent that the spacing of the grooves 76, 77 relative to one another will determine the spacing of the needles 20, 22 relative to one another. Further, it should be apparent that not 64 may be readily removed to permit the rapid substitution of a clamping plate 68 having a different groove spacing. Since the flat faces 80, 81 on the needles always engage the same vertical flat face 46 on carrier head 44, it is not necessary to disassemble the complete needle carrier and drive assembly, or any other components of the machine, to change the needle spacing. Since keyway 48 and the key 72 cooperate to accurately position the clamping plate 68, quick and accurate needle alignment is always assured.

While l have disclosed and described a preferred embodiment of my invention, i wish it understood that I do not intend to be restricted solely thereto, but that I do intend to include all embodiments thereof which would be apparent to one skilled in the art and which come within the spirit and scope of my invention.

What I claim is:

l. In a pivoted needle carrier for an overedge sewing machine including an arm adapted to be movably mounted on the machine, needle mounting means comprising, in combination, a head having a flat vertical face thereon, a clamping plate, fastener means mounting said clamping plate on said carrier with one surface thereof in opposed spaced relation to said face, key means interlocking said clamping plate and said head to prevent relative rotation therebetween, a pair of spaced grooves formed in said surface of said clamping plate, said grooves each being adapted to engage a cylindrical surface of the shank of a curved blade needle to clamp a flattened surface on said shank into engagement with said flat face to accurately align and position the needles in the machine, said clamping plate being interchangeable with similar plates having different groove spacing whereby the needle spacing in the machine may be readily changed to any desired spacing by selection of the appropriate clamping plate,

2. in a needle carrier as defined in claim 1, the further improvement wherein said key means comprises an elongated keyway formed in said flat face and an elongated key integrally formed on said one surface.

3. in a needle carrier as defined in claim 2, the further improvement wherein said spaced grooves are formed one on each side of said elongated key to accurately position the curved blade portion of said needles in the desired radial spacing relative to the pivot axis of said needle carrier.

4. in a needle carrier as defined in claim 2, the further improvement wherein said fastener means comprises an elongated bolt extending through said clampingplate and said head, said head having a recess formed merenfror receiving the head of said bolt, the walls of said recess engaging the head of said bolt to prevent rotation thereof. l I V 5. In a needle carrier for an overedge sewing machine including an elongated arm with a hub at one endthereof having bearing means therein pivotally supporting said carrier for oscillatory movement about an axis substantially perpendicular to the path of travel of a workpiece through the machine, and needle mounting means on the other end of said arm adapted to support a pair of needles for oscillatory movement with said carrier to simultaneously penetrate the workpiece at spaced points aligned along said path of travel, the improvement wherein said needle mounting means comprises, in com bination, a head integrally formed on said other end of said arm, a flat face on said head disposed in a plane substantially perpendicular to said axis and substantially parallel to said path of travel, an opening formed in and extending through said head centrally of said face, an elongated keyway formed in said face and extending substantially perpendicular to the axis of said opening, bolt means extending through said opening and projecting outwardly from said face, a clamping member having an opening therein mounted on said bolt means with a surface thereof in opposed substantially parallel relation to said face, an elongated key integrally formed on said clamping member and projecting outwardly from said surface, said key being dimensioned to be received in said keyway, said key and keyway cooperating to prevent relative rotation of said head and said clamping member about the axis of said bolt means, and a pair of spaced grooves formed in said surface one on each side of said key in position to receive the shank portion of a pair of needles to clamp said needles against said smooth face upon tightening of said bolt means. 

1. In a pivoted needle carrier for an overedge sewing machine including an arm adapted to be movably mounted on the machine, needle mounting means comprising, in combination, a head having a flat vertical face thereon, a clamping plate, fastener means mounting said clamping plate on said carrier with one surface thereof in opposed spaced relation to said face, key means interlocking said clamping plate and said head to prevent relative rotation therebetween, a pair of spaced grooves formed in said surface of said clamping plate, said grooves each being adapted to engage a cylindrical surface of the shank of a curved blade needle to clamp a flattened surface on said shank into engagement with said flat face to accurately align and position the needles in the machine, said clamping plate being interchangeable with similar plates having different groove spacing whereby the needle spacing in the machine may be readily changed to any desired spacing by selection of the appropriate clamping plate.
 2. In a needle carrier as defined in claim 1, the further improvement wherein said key means comprises an elongated keyway formed in said flat face and an elongated key integrally formed on said one surface.
 3. In a needle carrier as defined in claim 2, the further improvement wherein said spaced grooves are formed one on each side of said elongated key to accurately position the curved blade portion of said needles in the desired radial spacing relative to the pivot axis of said needle carrier.
 4. In a needle carrier as defined in claim 2, the further improvement wherein said fastener means comprises an elongated bolt extending through said clamping plate and said head, said head having a recess formed therein for receiving the head of said bolt, the walls of said recess engaging the head of said bolt to prevent rotation thereof.
 5. In a needle carrier for an overedge sewing machine including an elongated arm with a hub at one end thereof having bearing means therein pivotally supporting said carrier for oscillatory movement about an axis substantially perpendicular to the path of travel of a workpiece through the machine, and needle mounting means on The other end of said arm adapted to support a pair of needles for oscillatory movement with said carrier to simultaneously penetrate the workpiece at spaced points aligned along said path of travel, the improvement wherein said needle mounting means comprises, in combination, a head integrally formed on said other end of said arm, a flat face on said head disposed in a plane substantially perpendicular to said axis and substantially parallel to said path of travel, an opening formed in and extending through said head centrally of said face, an elongated keyway formed in said face and extending substantially perpendicular to the axis of said opening, bolt means extending through said opening and projecting outwardly from said face, a clamping member having an opening therein mounted on said bolt means with a surface thereof in opposed substantially parallel relation to said face, an elongated key integrally formed on said clamping member and projecting outwardly from said surface, said key being dimensioned to be received in said keyway, said key and keyway cooperating to prevent relative rotation of said head and said clamping member about the axis of said bolt means, and a pair of spaced grooves formed in said surface one on each side of said key in position to receive the shank portion of a pair of needles to clamp said needles against said smooth face upon tightening of said bolt means. 